Long Laminate for Printed Wiring Boards with Thin Fluororesin Layer
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Solution Overview
Problem
The existing long laminates for printed wiring boards face challenges in thinning the resin layer while maintaining high signal transmission speed and dimensional stability, as the stiffness of fluororesin films leads to wrinkles and reduced folding endurance.
Innovation Solution
A long laminate comprising a metal layer, a fluororesin layer, and a heat-resistant resin layer, with the fluororesin layer having a thickness of 1-10 μm and a ratio of total fluororesin to heat-resistant resin layer thickness between 0.3 and 3.0, and containing a dispersing agent in less than 2.0 mass%, produced using a method involving a liquid composition applied to a metal or heat-resistant resin film, which is then heated to form a smooth fluororesin layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fluororesin film is used to thin the resin layer for high signal transmission speed, then the signal transmission speed is improved, but wrinkles occur in the fluororesin layer due to low stiffness and dimensional stability
Solution Approach 1:
The patent uses a composite structure consisting of a fluororesin layer (for low permittivity and high signal transmission) and a heat-resistant resin layer (for dimensional stability and wrinkle prevention). This composite material approach allows the fluororesin layer to be thin (1-10 μm) while the heat-resistant resin layer provides the necessary mechanical support and stability during processing, preventing wrinkles while maintaining signal transmission performance.
2Volume of moving object
If the resin layer is thinned to reduce device size, then the device size is reduced, but the resistance of the conductor circuit increases making it difficult to increase signal transmission speed
Solution Approach 1:
The patent changes the material parameter (relative permittivity) of the resin layer by using fluororesin, which has inherently low permittivity. This allows the resin layer to be thinned (reducing device size) while maintaining low impedance and high signal transmission speed. The low permittivity of fluororesin compensates for the reduced layer thickness, preventing increase in conductor circuit resistance.
3Volume of moving object
If a fluororesin film is laminated with a heat-resistant resin film to achieve both thinning and dimensional stability, then the resin layer can be thinned, but wrinkles still occur due to the thinness and low stiffness of the fluororesin film
Solution Approach 1:
The patent segments the resin layer into two distinct functional layers: a thin fluororesin layer (1-10 μm) responsible for electrical performance and signal transmission, and a heat-resistant resin layer providing mechanical strength and dimensional stability. This segmentation allows each layer to optimize its specific function while working together, with the heat-resistant layer supporting the thin fluororesin layer to prevent wrinkles and improve folding endurance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a printed wiring board with a thin resin layer that supports high signal transmission speed, excellent dimensional stability, and improved folding endurance without wrinkles in the fluororesin layer.
Implementation Method 1
the wet film is heated to remove the following liquid medium and to melt the following resin powder
Implementation Method 2
the wet film is heated to remove the following liquid medium and to melt the following resin powder
Data Source
AI summary
Provided is a long laminate for a printed wiring board, which has reduced thickness of a resin layer and increased signal transmission speed, and which, while being excellent in dimensional stability and folding endurance, has no wrinkles in a fluororesin layer. The long laminate contains a metal layer of a long metal foil, a fluororesin layer containing a fluororesin and contacting the metal layer, and a heat-resistant resin layer containing a heat-resistant resin and contacting the fluororesin layer. Each fluororesin layer is 1 to 10 μm thick. The ratio of the total thickness of the fluororesin layer to the total thickness of the heat-resistant resin layer is 0.3 to 3.0. The sum of the total thickness of the fluororesin layer and the total thickness of the heat-resistant resin layer is at most 50 μm. Also provided are a method for producing the long laminate, and the printed wiring board.